362 On the Paragenetic Relations of Minerals. 



copper glance occurs, and as a rarity, digenite. At Saalfeld 

 the cupreous minerals occur in the lodes, especially above 

 the cupreous slate, and even when this is absent ; because, 

 as has been stated, the beds of zechstein are partially im- 

 pregnated with cupreous minerals ; rich deposits of fahlerz, 

 copper pyrites, and barytite, together with the numerous 

 products of these minerals, have been found here in zechstein. 

 The fahlerz generally contains cobalt, a fact which accounts 

 for the efflorescence of erythrine from it; the most usual de- 

 rivative is, however, the so-called ferruginous copper green. 

 Erythrine has been found upon fahlerz, and indeed upon 

 the crystal planes, where they appear somewhat decomposed, 

 without any other mineral containing cobalt being visible 

 among its associates. Such fahlerz contains even some ar- 

 senic. Still it is stated that rothnickelkies and spiess-cobalt 

 have been met with in lodes at a considerable elevation 

 above the cupreous slate. But all the minerals with a me- 

 tallic lustre here mentioned are known to occur at Saalfeld 

 in lodes, in cupreous slate, or immediately beneath it, the 

 latter especially at Kaulsdorf. 



According to Friesleben the cupreous slate, especially at 

 Mansfeld, appears to be richer near the riicken rather than 

 otherwise. This fact may be regarded as a further proof 

 that the metallic substances have generally accumulated 

 towards the riicken. 



Barytite as a lode substance, is a very constant associate 

 at all depths ; but it is remarkable that it is always more re- 

 cent than the fahlerz, and older than the pyritic minerals con- 

 taining cobalt and nickel. For this reason, perhaps, the 

 fahlerz is wanting in the riicken of copper — slate, and weiss- 

 liegenden, heavy spar being there the oldest member. Calc- 

 spar and arragonite appear as more recent members, and it 

 is only in some few instances that there is a second genera- 

 tion of copper pyrites, almost solely in very small crystals 

 upon the calc-spar. In the immense and long-worked 

 deposits of brown iron ore at Kbnitz, Kamsdorf, and Saalfeld, 

 which belong to the zechstein, and have, perhaps, entirely 

 originated from spathic iron, as is indicated by the frequent 

 pseudomorphs, and the association of compact and frothy 



